linux-toradex.git/fs/eventpoll.c, branch v3.2-rt10

epoll.patch

2012-01-16T19:00:32+00:00

Signed-off-by: Thomas Gleixner

epoll: fix spurious lockdep warnings

2011-11-01T00:30:57+00:00

epoll can acquire recursively acquire ep->mtx on multiple "struct
eventpoll"s at once in the case where one epoll fd is monitoring another
epoll fd.  This is perfectly OK, since we're careful about the lock
ordering, but it causes spurious lockdep warnings.  Annotate the recursion
using mutex_lock_nested, and add a comment explaining the nesting rules
for good measure.

Recent versions of systemd are triggering this, and it can also be
demonstrated with the following trivial test program:

--------------------8<--------------------

int main(void) {
   int e1, e2;
   struct epoll_event evt = {
       .events = EPOLLIN
   };

   e1 = epoll_create1(0);
   e2 = epoll_create1(0);
   epoll_ctl(e1, EPOLL_CTL_ADD, e2, &evt);
   return 0;
}
--------------------8<--------------------

Reported-by: Paul Bolle 
Tested-by: Paul Bolle 
Signed-off-by: Nelson Elhage 
Acked-by: Jason Baron 
Cc: Dave Jones 
Cc: Davide Libenzi 
Cc: 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'master' into for-next

2011-09-15T13:08:18+00:00

Fast-forward merge with Linus to be able to merge patches
based on more recent version of the tree.

atomic: use

2011-07-26T23:49:47+00:00

This allows us to move duplicated code in 
(atomic_inc_not_zero() for now) to 

Signed-off-by: Arun Sharma 
Reviewed-by: Eric Dumazet 
Cc: Ingo Molnar 
Cc: David Miller 
Cc: Eric Dumazet 
Acked-by: Mike Frysinger 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

eventpoll: fix comment typo 'evenpoll'

2011-07-26T09:44:54+00:00

Signed-off-by: Paul Bolle 
Signed-off-by: Jiri Kosina

Fix common misspellings

2011-03-31T14:26:23+00:00

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi

epoll: fix compiler warning and optimize the non-blocking path

2011-03-23T00:44:15+00:00

Add a comment to ep_poll(), rename labels a bit clearly, fix a warning of
unused variable from gcc and optimize the non-blocking path a little.

Hinted-by: Andrew Morton 
Signed-off-by: Davide Libenzi 

hannes@cmpxchg.org:

: The non-blocking ep_poll path optimization introduced skipping over the
: return value setup.
:
: Initialize it properly, my userspace gets upset by epoll_wait() returning
: random things.
:
: In addition, remove the reinitialization at the fetch_events label, the
: return value is garuanteed to be zero when execution reaches there.

[hannes@cmpxchg.org: fix initialization]
Signed-off-by: Johannes Weiner 
Cc: Shawn Bohrer 
Acked-by: Davide Libenzi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

epoll: move ready event check into proper inline

2011-03-23T00:44:15+00:00

Move the event readiness check into a proper inline, and use it uniformly
inside ep_poll() code.  Events in the ->ovflist are no less ready than the
ones in ->rdllist.

Signed-off-by: Davide Libenzi 
Cc: Shawn Bohrer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2011-03-18T17:37:40+00:00

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (47 commits)
  doc: CONFIG_UNEVICTABLE_LRU doesn't exist anymore
  Update cpuset info & webiste for cgroups
  dcdbas: force SMI to happen when expected
  arch/arm/Kconfig: remove one to many l's in the word.
  asm-generic/user.h: Fix spelling in comment
  drm: fix printk typo 'sracth'
  Remove one to many n's in a word
  Documentation/filesystems/romfs.txt: fixing link to genromfs
  drivers:scsi Change printk typo initate -> initiate
  serial, pch uart: Remove duplicate inclusion of linux/pci.h header
  fs/eventpoll.c: fix spelling
  mm: Fix out-of-date comments which refers non-existent functions
  drm: Fix printk typo 'failled'
  coh901318.c: Change initate to initiate.
  mbox-db5500.c Change initate to initiate.
  edac: correct i82975x error-info reported
  edac: correct i82975x mci initialisation
  edac: correct commented info
  fs: update comments to point correct document
  target: remove duplicate include of target/target_core_device.h from drivers/target/target_core_hba.c
  ...

Trivial conflict in fs/eventpoll.c (spelling vs addition)

epoll: prevent creating circular epoll structures

2011-02-25T23:07:36+00:00

In several places, an epoll fd can call another file's ->f_op->poll()
method with ep->mtx held.  This is in general unsafe, because that other
file could itself be an epoll fd that contains the original epoll fd.

The code defends against this possibility in its own ->poll() method using
ep_call_nested, but there are several other unsafe calls to ->poll
elsewhere that can be made to deadlock.  For example, the following simple
program causes the call in ep_insert recursively call the original fd's
->poll, leading to deadlock:

 #include 
 #include 

 int main(void) {
     int e1, e2, p[2];
     struct epoll_event evt = {
         .events = EPOLLIN
     };

     e1 = epoll_create(1);
     e2 = epoll_create(2);
     pipe(p);

     epoll_ctl(e2, EPOLL_CTL_ADD, e1, &evt);
     epoll_ctl(e1, EPOLL_CTL_ADD, p[0], &evt);
     write(p[1], p, sizeof p);
     epoll_ctl(e1, EPOLL_CTL_ADD, e2, &evt);

     return 0;
 }

On insertion, check whether the inserted file is itself a struct epoll,
and if so, do a recursive walk to detect whether inserting this file would
create a loop of epoll structures, which could lead to deadlock.

[nelhage@ksplice.com: Use epmutex to serialize concurrent inserts]
Signed-off-by: Davide Libenzi 
Signed-off-by: Nelson Elhage 
Reported-by: Nelson Elhage 
Tested-by: Nelson Elhage 
Cc: 		[2.6.34+, possibly earlier]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds